1. Field of the Invention
The present invention is related generally to biocompatible coatings. More specifically, the present invention is related to a modification of the chemical structure of the biocompatible coating to increase its mechanical stability on a surface of a substrate.
2. Background Art
Implantable medical devices including, pacemakers, defibrillators, neurostimulators, venous introducers, and catheters are devices that are well known to help improve health and sustain life. However, despite the significant benefits that implantable medical devices provide, their use could lead to thrombosis, a serious medical problem that could result in death. Thrombosis is the formation of a blood clot within a blood vessel that obstructs blood flow leading to possible stroke, heart attack, organ failure and death.
Medical device related thrombosis initially occurs as a result of an interaction between blood and the surface of the medical device when they are in contact with each other. Once blood is in contact with the medical device, blood platelets and other blood constituents begin to coagulate and clot on the device surface. Blood clotting is known to occur on both metallic and polymeric materials, materials which are used to manufacture medical devices.
After the formation of the blood clots have occurred on the device surface, the clots could break off from the surface, travel through the blood stream, become lodged in a blood vessel and obstruct blood flow. Thrombosis is an especially major problem for permanently implanted devices that are in continuous blood contact.
A great deal of work has been done to develop coatings which reduce cell adhesion and activation. These coatings, referred to as biomimetic coatings, can inhibit the formation of blood clots and, therefore, reduce the possibility of thrombosis from occurring.
One such family of biomimetic coatings are surfactants described by Marchant et al. in U.S. Pat. Nos. 6,759,388 and 7,276,474 and U.S. patent application publications 20080247988 and 20080262614, which are herein incorporated by reference.
These coatings provide good blood clot inhibition. However, these coatings, which are adhered to many medical device surfaces, particularly those that are in constant contact with blood, could benefit from improved mechanical stability. In particular, these devices are often subjected to surface abrasion during handling prior to implantation, or while in use, which could remove the biomimetic coating from their surface. In addition, these coatings are often subjected to increased shear stresses during implantation that could lead to degradation of the coating over time. Degradation may include cracking, scratching, delamination, or spalling of the coating. Furthermore, such coatings may also be subject to dissolution in the body once implanted.
Therefore, there is a need to provide a means of modifying the biomimetic coating to improve its mechanical stability on the surface of a medical device surfaces. Specifically, a biomimetic coating with improved resistance to cracking, scratching, spalling, chemical dissolution and surface adhesion is provided.